3B Scientific Fine Beam Tube T - Manual (Page 4)

UE307070 3B SCIENTIFIC® PHYSICS EXPERIMENT
3B Scientific GmbH, Rudorffweg 8, 21031 Hamburg, Germany, www.3bscientific.com
Table 2: Values calculated from Table 1 in relation to accel-
erating voltage U for circular paths of three different con-
stant radii
B 2 r 2 /mT 2 cm 2
U/V 2 U/V
for r = 3 cm for r = 4 cm for r = 5 cm
300 600 36.4 35.8 35.7
280 560 33.7 33.4 33.4
260 520 31.4 31.0 30.5
240 480 28.9 28.6 28.8
220 440 27.0 25.8 25.7
200 400 23.6 23.7 22.3
B r 2 2 2 2 / mT cm
10 0
0
200
400
600
20 30 40
2 / V U
Fig. 4: Graph of r 2 B 2 against 2U for values as measured
(black: r = 5 cm, red: r = 4 cm, green: r = 3 cm)
The slope of the straight line through the origin corresponds
to the specific charge of the electron e/m.